1. Field of the Invention
The present invention relates to apparatus and an associated method for facilitating positioning of a patient in such a manner as to maximize the efficiency of the patient's imaging and/or therapeutic procedures and, more specifically, the invention is directed toward a system which automatically repositions a portion of a patient's body which is of interest and has moved during a medical procedure.
2. Description of the Prior Art
It has long been known that for various forms of diagnostic imaging, as well as radiotherapy, that proper immobilization of the portion of the patient's body being imaged or treated will contribute meaningfully to the clarity and resolution of image and efficiency of therapy. With respect to the use of x-rays as in x-ray computed tomography, purely anatomical information is obtained at a very rapid rate.
With respect to improved technology such as that used in positron emission tomography (PET), magnetic resonance imaging (MRI), or radiotherapy may require immobilizing the portion of the patient's body for periods of from 10 seconds to 20 minutes. Motion of the patient body portion of interest during this period can cloud the image and interfere with efficiency of therapy. Among the advantages of PET is the ability to obtain functional information regarding a portion of the patient's body, such as the brain.
In PET, radiotracers which are designed to be substrates for various biological processes, may be injected into the body. These compounds can be constructed around a cyclotron-produced positron-emitting nuclide of a biologically occurring element such as .sup.11 C, .sup.5 O and .sup.18 F. By way of a specific example, the PET radiotracer [.sup.18 F]2-fluoro-2-deoxyglucose (FDG)] is a known substrate for energy metabolism. FDG can be used to locate small cancerous tumors throughout the body as well as to assess stroke damage to the brain.
Specific PET radiotracers have been developed in recent years to image complex aspects of brain function which may be used in the diagnosis and study of serious neurodegenerative and neuropsychiatric illnesses, such as Alzheimer's Disease, Schizophrenia and Parkinson's Disease. PET studies have also been useful tools in mapping functional organization of the normal human brain.
PET cameras are now capable of imaging a 20 cm or larger axial field of view in three dimension with a spatial resolution of less than 2.0 mm. As increased efforts are made to study smaller and smaller structures within the brain, movement of the patient's head during such studies contributes more significantly to reduction in resolution and the presence of undesirable movement artifacts. Similar problems exist in respect of magnetic resonance imaging (MRI) which may have a spatial resolution greater than an order of magnitude larger than PET.
It has been known to reduce patient head movement and the accompanying blurring of image and loss of contrast and resolution by providing a head support underlying the patient and a thermoplastic face mask which is molded to the patient's head and secured to the head support.
It has been suggested to employ optical tracking systems to monitor such movement and to attempt to correct the variations in data due to undesired patient movement.
There remains, therefore, a very substantial need for improved means of minimizing the detrimental effect on diagnostic and therapeutic procedures resulting from undesired patient movement.